What is the concentration (in mol/L) of Co2+(aq) in a solution of 8.77 grams of cobalt (II) nitrate hexahydrate, Co(NO3)2.6H2O dissolved in water to a total solution volume of 250 mL?
8.77grams= 8.77/291 moles
So the moles of Co ion is the same.
Molarity= molesCoion/.250
To find the concentration of Co2+(aq) in the solution, we need to follow these steps:
1. Calculate the number of moles of Co(NO3)2.6H2O:
- Co(NO3)2.6H2O is a hydrated compound, so we need to determine the molecular weight of the compound including water molecules.
- Molecular weight of Co(NO3)2: cobalt (Co) = 58.9332 g/mol, nitrogen (N) = 14.0067 g/mol, oxygen (O) = 15.999 g/mol
- Molecular weight of H2O: hydrogen (H) = 1.00784 g/mol, oxygen (O) = 15.999 g/mol
- Co(NO3)2 = (58.9332 g/mol) + 2(14.0067 g/mol) + 6(15.999 g/mol) = 291.0642 g/mol
- H2O = (2(1.00784 g/mol) + 15.999 g/mol) = 18.01528 g/mol
- Molecular weight of Co(NO3)2.6H2O:
- (291.0642 g/mol) + 6(18.01528 g/mol) = 407.01548 g/mol
- Number of moles = mass (in grams) / molecular weight
- Moles of Co(NO3)2.6H2O = 8.77 g / 407.01548 g/mol
2. Calculate the concentration of Co2+(aq):
- Concentration = moles / volume (in liters)
- Concentration = (moles of Co(NO3)2.6H2O) / (volume of solution in liters)
- Volume of solution = 250 mL = 250/1000 L
- Concentration = (moles of Co(NO3)2.6H2O) / (volume of solution in L)
Now you can substitute the values into the equation to get the final answer.